Inkjet ink formulation

ABSTRACT

An inkjet ink includes a mixture of a phthalocyanine dye and a rhodamine magenta dye in an ink vehicle, wherein the inkjet ink has a chroma C* value of approximately 60 to approximately 90.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to U.S. patent application Ser. No.10/891,760, filed on even date herewith, assigned to the assignee of thepresent invention, and incorporated herein by reference.

BACKGROUND

An inkjet printing system may include a printhead and an ink supplywhich supplies liquid ink to the printhead. The printhead ejects inkdrops through a plurality of orifices or nozzles and toward a printmedia, such as a sheet of paper, so as to print onto the print media.Typically, the nozzles are arranged in one or more arrays such thatproperly sequenced ejection of ink from the nozzles causes characters orother images to be printed upon the print media as the printhead and theprint media are moved relative to each other.

In general, inkjet inks are either dye-based or pigment-based. Both aretypically prepared in an ink vehicle that contains the dye and/or thepigment. Dye-based inkjet inks generally use a colorant which isdissolved in the ink vehicle and pigment-based inks generally use acolorant that is insoluble in the ink vehicle, but suspended ordispersed in the form of small particles.

Perceived color quality of inkjet inks can be characterized using anyone of several color space systems, such as Munsell or CIELAB, as iswell known in the art. With respect to the Munsell color space, a givencolor is defined using three terms, namely Hue (H), Value (V), andChroma (C). With respect to the CIELAB color space, a color is definedusing three terms L*, a*, and b*. With the CIELAB system, L* defines thelightness of a color and ranges from 0 (black) to 100 (white). Inaddition, the terms a* and b* may be used to define the hue and chromaof a color, where a* ranges from a negative number (green) to a positivenumber (red) and b* ranges from a negative number (blue) to a positivenumber (yellow). The additional terms of h° (hue angle) and C* (chroma)are also used to further describe a given color, as is known to thoseskilled in the art. As such, the Munsell H, V, and C values or theCIELAB L*, a*, and b* values can be used to calculate a volume of colorspace that a specific ink set can produce, whereby the larger the colorspace volume the more colors the ink set is capable of producing.

Desirable properties of inkjet inks include good crusting resistance,good stability, proper viscosity, proper surface tension, littlecolor-to-color bleed, rapid dry time, no deleterious reaction withprinthead components, high solubility of the dyes in the ink vehicle,consumer safety, low strike through, high color saturation, good dotgain, and suitable color characteristics. Furthermore, the durability ofthe printed image, for example, light and water fastness, alsocontributes to the quality of a printed inkjet image.

Known inkjet inks may possess one or more of the above describedproperties. Few inkjet inks, however, possess all of these propertiessince an improvement in one property often results in the degradation ofanother property. Accordingly, efforts continue in developing inkformulations that have improved properties while minimizing thedegradation of others. However, challenges still remain to furtherimprove the image quality and lightfastness of inkjet inks withoutsacrificing pen performance and/or reliability.

SUMMARY

One aspect of the present invention provides an inkjet ink including amixture of a phthalocyanine dye and a rhodamine magenta dye in an inkvehicle, wherein the inkjet ink has a chroma C* value of approximately60 to approximately 90.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating one embodiment of an inkjetprinting system.

FIG. 2 is a schematic illustration of one embodiment of an ink setincluding light cyan ink, light magenta ink, and blue ink.

FIG. 3 is a schematic illustration of one embodiment of an ink setincluding light cyan ink, light magenta ink, blue ink, cyan ink, magentaink, and yellow ink.

FIG. 4 is a schematic illustration of one embodiment of an ink setincluding light cyan ink, light magenta ink, blue ink, cyan ink, magentaink, yellow ink, light gray ink, medium gray ink, and black.

FIG. 5 is a graph of one embodiment of a color space of an ink setaccording to the present invention.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings which form a part hereof, and in which is shown byway of illustration specific embodiments in which the invention may bepracticed. It is to be understood that other embodiments may be utilizedand structural or logical changes may be made without departing from thescope of the present invention. The following detailed description,therefore, is not to be taken in a limiting sense, and the scope of thepresent invention is defined by the appended claims.

FIG. 1 illustrates one embodiment of a portion of an inkjet printingsystem 10. Inkjet printing system 10 includes an inkjet printheadassembly 12, an ink supply assembly 14, a carriage assembly 16, a mediatransport assembly 18, and an electronic controller 20. Inkjet printheadassembly 12 includes one or more printheads which eject drops of inkthrough a plurality of orifices or nozzles 13.

In one embodiment, the drops of ink are directed toward a medium, suchas a print media 19, so as to print onto print media 19. Nozzles 13 maybe arranged in one or more columns or arrays such that properlysequenced ejection of ink from nozzles 13 causes characters, symbols,and/or other graphics or images to be printed upon print media 19 asinkjet printhead assembly 12 and print media 19 are moved relative toeach other.

Print media 19 may include any type of suitable sheet material, such aspaper, card stock, envelopes, labels, transparencies, Mylar, and thelike. Print media 19 may include a cut-sheet material or a continuousform or continuous web print media such as a continuous roll ofunprinted paper.

Ink supply assembly 14 supplies ink to inkjet printhead assembly 12 andincludes a reservoir 15 for storing ink. As such, in one embodiment, inkflows from reservoir 15 to inkjet printhead assembly 12. In oneembodiment, inkjet printhead assembly 12 and ink supply assembly 14 arehoused together in an inkjet print cartridge or pen, as identified bydashed line 30. In another embodiment, ink supply assembly 14 isseparate from inkjet printhead assembly 12 and supplies ink to inkjetprinthead assembly 12 through an interface connection, such as a supplytube. In either embodiment, reservoir 15 of ink supply assembly 14 maybe removed, replaced, and/or refilled.

Carriage assembly 16 positions inkjet printhead assembly 12 relative tomedia transport assembly 18, and media transport assembly 18 positionsprint media 19 relative to inkjet printhead assembly 12. As such, aprint region 17 within which inkjet printhead assembly 12 deposits inkdrops is defined adjacent to nozzles 13 in an area between inkjetprinthead assembly 12 and print media 19. In one embodiment, print media19 is advanced through print region 17 during printing by mediatransport assembly 18.

Electronic controller 20 communicates with inkjet printhead assembly 12,carriage assembly 16, and media transport assembly 18. Electroniccontroller 20 receives data 21 from a host system, such as a computer,and may include memory for temporarily storing data 21. Data 21 may besent to inkjet printing system 10 along an electronic, infrared, opticalor other information transfer path. Data 21 represents, for example, animage, graphics, or pattern to be printed. As such, data 21 forms aprint job for inkjet printing system 10 and includes one or more printjob commands and/or command parameters.

In one embodiment, electronic controller 20 provides control of inkjetprinthead assembly 12 including timing control for ejection of ink dropsfrom nozzles 13. As such, electronic controller 20 defines a pattern ofejected ink drops which form characters, symbols, and/or other graphicsor images on print media 19. Timing control and, therefore, the patternof ejected ink drops, is determined by the print job commands and/orcommand parameters. In one embodiment, logic and drive circuitry forminga portion of electronic controller 20 is located on inkjet printheadassembly 12. In another embodiment, logic and drive circuitry forming aportion of electronic controller is located off inkjet printheadassembly 12.

FIG. 2 illustrates one embodiment of an ink set 100 for inkjet printingsystem 10. In one embodiment, ink set 100 includes a light cyan (c) ink102, a light magenta (m) ink 104, and a blue (B) ink 106. In oneembodiment, light cyan ink 102, light magenta ink 104, and blue ink 106are dye-based inks and are formulated to produce a large color gamut andhave desirable lightfastness to enable the production of high-qualityimages. Inks formulated according to the present invention produceimages having color appearances that meet desirable properties of coloraccuracy and durability.

In one embodiment, ink set 100 is provided by a single inkjet pen orcartridge including separate chambers for each of the inks. Thus, in oneembodiment, ink set 100 is provided by a tri-chamber inkjet pen orcartridge including a chamber for light cyan ink 102, a chamber forlight magenta ink 104, and a chamber for blue ink 106. In anotherembodiment, ink set 100 is provided by individual or separate inkjetpens or cartridges for each of the inks. Thus, in one embodiment, inkset 100 is provided by an inkjet pen including light cyan ink 102, aninkjet pen including light magenta ink 104, and an inkjet pen includingblue ink 106.

FIG. 3 illustrates another embodiment of an ink set 110 for inkjetprinting system 10. In one embodiment, ink set 110 includes light cyanink 102, light magenta ink 104, and blue ink 106 of ink set 100, asdescribed above, as well as a cyan (C) ink 112, a magenta (M) ink 114,and a yellow (Y) ink 116. As such, light cyan ink 102, light magenta ink104, blue ink 106, cyan ink 112, magenta ink 114, and yellow ink 116form a 6-ink printing system (cmBCMY).

In one embodiment, similar to light cyan ink 102, light magenta ink 104,and blue ink 106, cyan ink 112, magenta ink 114, and yellow ink 116 ofink set 110 are dye-based inks and are formulated to produce a largecolor gamut and have desirable lightfastness to enable the production ofhigh-quality images. In addition, similar to that described above withreference to ink set 100, cyan ink 112, magenta ink 114, and yellow ink116 of ink set 110 may be provided by a single inkjet pen or cartridgeincluding separate chambers for each of the inks or by individual orseparate inkjet pens or cartridges for each of the inks.

In one embodiment, the light inks of ink set 100 and the correspondinginks of ink set 110, namely light cyan ink 102 and cyan ink 112 andlight magenta ink 104 and magenta ink 114 of ink sets 100 and 110,respectively, are distinguished by dye load. For example, in oneembodiment, light cyan ink 102 of ink set 100 has a dye load ofapproximately 0.1 percent to approximately 2.0 percent by weight andlight magenta ink 104 of ink set 100 has a dye load of approximately 0.1percent to approximately 2.0 percent by weight. In addition, cyan ink112 of ink set 110 has a dye load of approximately 2.0 percent toapproximately 10.0 percent by weight and magenta ink 114 of ink set 110has a dye load of approximately 2.0 percent to approximately 10.0percent by weight.

In one embodiment, the light inks of ink set 100, namely light cyan ink102 and light magenta ink 104, and the corresponding inks of ink set110, namely cyan ink 112 and magenta ink 114, are distinguished byprinted lightness values. In one embodiment, the lightness values are L*values as defined by the CIELAB color space system. The CIELAB colorspace system is based upon standards promulgated by the InternationalCommittee on Illumination or CIE (Commission Internationale de'L'Eclairage) in 1976. According to such standards, an L* value of 100generally equals an ideal diffused perfectly white reflector. As such,with the CIELAB system, L* defines the lightness of a color and rangesfrom 0 (black) to 100 (white).

In one embodiment, the light inks of ink set 100 have printed lightnessvalues greater than those of the corresponding inks of ink set 110. Morespecifically, light cyan ink 102 and light magenta ink 104 of ink set100 have respective lightness values and cyan ink 112 and magenta ink114 of ink set 110 have respective lightness values such that thelightness values of light cyan ink 102 and light magenta ink 104 aregreater than the respective lightness values of cyan ink 112 and magentaink 114. In one embodiment, for example, light cyan ink 102 and lightmagenta ink 104 each have a lightness L* value of approximately 60 toapproximately 85, and cyan ink 112 and magenta ink 114 each have alightness L* value of approximately 35 to approximately 55.

In one embodiment, light cyan ink 102 and light magenta ink 104 of inkset 100 mix to form a composite blue on print media 19. Accordingly, thecomposite blue has a printed lightness value. As such, in oneembodiment, formulations of light cyan ink 102, light magenta ink 104,and/or blue ink 106 are selected such that blue ink 106 has a lightnessvalue that is approximately one-half the lightness value of thecomposite blue formed by light cyan ink 102 and light magenta ink 104.Conversely, the lightness value of the composite blue formed by lightcyan ink 102 and light magenta ink 104 is approximately twice thelightness value of blue ink 106. Thus, light cyan ink 102, light magentaink 104, and blue ink 106 of ink set 100 may be used to print a widerange of lightness values.

In one embodiment, when used in a 6-ink printing system (cmBCMY) asdescribed above, blue ink 106 of ink set 100 is mixed with yellow ink116 of ink set 110 to form black on print media 19. As such, a separateinkjet pen or chamber of an inkjet pen including black ink may beexcluded from the printing system thus increasing versatility of theprinting system.

FIG. 4 illustrates another embodiment of an ink set 120 for inkjetprinting system 10. In one embodiment, ink set 120 includes light cyanink 102, light magenta ink 104, and blue ink 106 of ink set 100, asdescribed above, cyan ink 112, magenta ink 114, and yellow ink 116 ofink set 110, as described above, as well as a light gray (g) ink 122, amedium gray (G) ink 124, and a black (z) ink 126. As such, light cyanink 102, light magenta ink 104, blue ink 106, cyan ink 112, magenta ink114, yellow ink 116, light gray ink 122, medium gray ink 124, and blackink 126 form a 9-ink printing system (cmBCMYgGz).

In one embodiment, light gray ink 122, medium gray ink 124, and blackink 126 are dye-based inks and are formulated to produce a large colorgamut and have desirable lightfastness to enable the production ofhigh-quality images. In addition, similar to that described above withreference to ink sets 100 and 110, light gray ink 122, medium gray ink124, and black ink 126 of ink set 120 may be provided by a single inkjetpen or cartridge including separate chambers for each of the inks orprovided by individual or separate inkjet pens or cartridges for each ofthe inks.

In one embodiment, light gray ink 122, medium gray ink 124, and blackink 126 of ink set 120 are distinguished by printed lightness values.More specifically, in one embodiment, light gray ink 122 has a lightnessvalue greater than that of medium gray ink 124, and medium gray ink 124has a lightness value greater than that of black ink 126. In oneembodiment, the lightness values are L* values of the CIELAB color spacesystem, as described above. In one embodiment, for example, light grayink 122 has a lightness L* value of approximately 50 to approximately70, medium gray ink 124 has a lightness L* value of approximately 25 toapproximately 50, and black ink 126 has a lightness L* value ofapproximately 0 to approximately 5.

In one embodiment, blue ink 106 of ink set 100 is selected so as to havea relatively high chroma. Chroma refers to the relative colorfulness ofa given color. More specifically, chroma is known in the art as thecolorfulness of an area judged in proportion to the brightness of asimilarly illuminated area that appears to be white. In the CIELABsystem, chroma (C*) is defined by the following equation:C*=(a*2+b*2)where a* ranges from a negative number (green) to a positive number(red) and b* ranges from a negative number (blue) to a positive number(yellow). In addition, in the CIELAB system, hue or hue angle (h°) isdefined by the following equation:h°=tan−1b*/a*

In one embodiment, as described below, a formulation of blue ink 106 isselected such that blue ink 106 has a chroma C* value of approximately60 to approximately 90. In one exemplary embodiment, the chroma C* valueof blue ink 106 is approximately 80. In addition, in one embodiment, thelightness L* value of blue ink 106 is approximately 25 to approximately35 and the hue h° value of blue ink 106 is approximately 270 toapproximately 290. In one exemplary embodiment, the lightness L* valueof blue ink 106 is approximately 27 and the hue h° value of blue ink 106is approximately 288.

In one embodiment, blue ink 106 of ink set 100 includes a mixture of aphthalocyanine dye and a rhodamine magenta dye in an ink vehicle. Inkvehicles are well known in the art and refer to the vehicle in which acolorant, such as a selected dye or dyes, is placed to form the ink. Awide variety of ink vehicles in varying amounts may be used with the inkformulations of the present invention. Such ink vehicles may include amixture of a variety of different components including, for example,ingredients such as solvents, buffers, biocides, viscosity modifiers,surface-active agents (surfactants), salts, metal chelators, and water.

In one embodiment, the formulation of blue ink 106 is defined by apercent by weight of the selected dyes. In one embodiment, for example,the amount of phthalocyanine dye is between about 2 percent by weightand about 4 percent by weight of the ink formulation. In addition, theamount of rhodamine magenta dye is between about 1 percent by weight andabout 2 percent by weight of the ink formulation. In one exemplaryembodiment, the amount of phthalocyanine dye is about 3.5 percent byweight of the ink formulation. In addition, the amount of rhodaminemagenta dye is about 1.5 percent by weight of the ink formulation.

In one embodiment, the phthalocyanine dye of blue ink 106 is a cyan dyehaving a more bluish hue. Examples of phthalocyanine dyes suitable forblue ink 106 include Direct Blue 199 (DB199) dyes having the followingstructure:

wherein each R group is independently H, SO₃H, SO₂NH₂, or SO₂NH-alkyl-OHwith the proviso that an average of from 2 to 6 R groups are other thanH. In one embodiment, the phthalocyanine dye is a sulfonated dye with adegree of aggregation of the cyan being increased by tuning the degreeof substitution by sulfoneamine, sulfoneamide, and sulfate groups. Inone exemplary embodiment, the phthalocyanine dye is DB199.

In one embodiment, the rhodamine magenta dye of blue ink 106 has apurple hue. Examples of rhodamine magenta dyes suitable for blue ink 106include Acid Red 52, Acid Red 289, Acid Red 388, and mixtures thereof.In one exemplary embodiment, the rhodamine magenta dye of blue ink 106is Acid Red 52 (AR52) available, for example, from Avecia Limited,Manchester, UK.

In one embodiment, the ink formulation of blue ink 106 also includes ametal-stabilized or metalized magenta dye. The metalized magenta dye,for example, helps stabilize the rhodamine magenta dye from light fade.A metalized magenta dye is defined as a magenta dye which includes ametal ion complex. Various methods for complexing metal ions to organicchemical groups, such as by chelation, are known to those skilled in theart. Furthermore, a variety of metal ions, such as nickel, copper,cobalt, and iron may be used to create the metal ion complex.

In one embodiment, the metalized magenta dye is a copper- ornickel-containing azo dye. In one embodiment, the amount of metalizedmagenta dye is between about 0.1 percent by weight and about 10 percentby weight of the ink formulation.

With respect to the copper- or nickel-containing azo dye, any functionaldye that meets these criteria can be used. Examples include CI ReactiveRed 23, and CI Reactive Red 23 in the pacified form. An example of sucha Reactive Red 23 in the pacified form includes the following structure:

wherein each M can be H or a monovalent ion such as Na⁺, Li⁺, K⁺, NH₄ ⁺,and combinations thereof. Alternative examples include nickel metalizednaphthol azo triazole dyes, and dyes having the following structure:

wherein M can be H or a monovalent ion such as Na⁺, Li⁺, K⁺, NH₄ ⁺, andcombinations thereof. Though the dye(s) shown above are functionalizedwith SO₃ (or SO₃M) groups at specific locations, this is provided byexample only. One skilled in the art would recognize that othersolubilizing groups or other locations can be functionalized withsimilar success. Such modifications are included herein. As mentioned,the copper- or nickel-containing azo dye can be a single copper- ornickel-containing azo dye, or can be at least two copper- ornickel-containing azo dyes blended together.

EXAMPLES

Different inks were formulated and qualities of the formulated inks weremeasured in an effort to assess the benefits of the present invention.Namely, the effect of different amounts of each dye component on thevalues of lightness, chroma, and hue was measured. In one embodiment,three different ink formulations were prepared having the followingcompositions:

TABLE 1 Ink Formulation 1.1 Ingredient Wt % DYES Phthalocyanine dye 2.3Acid Red 52 Na 1.0 COMPONENTS 2-ethyl-2-hydroxymethyl-1,3-propane diol7.50 2-Pyrrolidone 6.50 1,5 Pentanediol 8.00 Tergitol 15-S-7 1.00Tergitol 15-S-5 1.00 MES Sodium salt 0.20 DOWFAX8390 0.40 EDTA Na20.0075 Mg(NO3)2*6H20 3.00 Water to 100

TABLE 2 Ink Formulation 1.2 Ingredient Wt % DYES Phthalocyanine dye2.875 Acid Red 52 Na 1.25 COMPONENTS 2-ethyl-2-hydroxymethyl-1,3-propanediol 7.50 2-Pyrrolidone 6.50 1,5 Pentanediol 8.00 Tergitol 15-S-7 1.00Tergitol 15-S-5 1.00 MES Sodium salt 0.20 DOWFAX8390 0.40 EDTA Na20.0075 Mg(NO3)2*6H20 3.00 Water to 100

TABLE 3 Ink Formulation 1.3 Ingredient Wt % DYES Phthalocyanine dye 3.45Acid Red 52 Na 1.50 COMPONENTS 2-ethyl-2-hydroxymethyl-1,3-propane diol7.50 2-Pyrrolidone 6.50 1,5 Pentanediol 8.00 Tergitol 15-S-7 1.00Tergitol 15-S-5 1.00 MES Sodium salt 0.20 DOWFAX8390 0.40 EDTA Na20.0075 Mg(NO3)2*6H20 3.00 Water to 100

While all of the inks had the same ink vehicles and included aphthalocyanine dye and a rhodamine magenta dye of Acid Red 52, each haddifferent weight percentages of phthalocyanine dye and Acid Red 52. Forexample, ink formulation 1.1 had 2.3 percent by weight phthalocyaninedye and 1.0 percent by weight Acid Red 52, ink formulation 1.2 had 2.875percent by weight phthalocyanine dye and 1.25 percent by weight Acid Red52, and ink formulation 1.3 had 3.45 percent by weight phthalocyaninedye and 1.50 percent by weight Acid Red 52.

Lightness (L*), chroma (C*), and hue (h°) for each of the inkformulations identified above was measured and is provided in Table 4below. As shown in Table 4, chroma is increased with the ink formulation1.3.

TABLE 4 Color Comparison Lightness Chroma Hue Ink Formulation (L*) (C*)(h°) 1.1 34.8 75.6 284.7 1.2 31.26 78.44 286.45 1.3 27.7 80.6 288

FIG. 5 illustrates one embodiment of a color space for an ink setincluding a cmB ink set, such as ink set 100 including high chroma blueink 106 as described above, as compared with an ink set devoid of blueink 106. As noted from the graph, the color gamut or volume of the colorspace is expanded with blue ink 106 in the ink set.

Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat a variety of alternate and/or equivalent implementations may besubstituted for the specific embodiments shown and described withoutdeparting from the scope of the present invention. This application isintended to cover any adaptations or variations of the specificembodiments discussed herein. Therefore, it is intended that thisinvention be limited only by the claims and the equivalents thereof.

1. An inkjet ink, comprising: a mixture of a phthalocyanine dye and a rhodamine magenta dye in an ink vehicle, wherein the inkjet ink has a chroma C* value of approximately 60 to approximately 90; wherein the phthalocyanine dye comprises a dye including the structure:

and wherein each R group is independently H, SO₃H, SO₂NH₂, or SO₂NH-alkyl-OH, with the proviso that an average of from 2 to 6 R groups are other than H and at least one of the R groups is SO₂NH-alkyl-OH.
 2. The inkjet ink of claim 1, wherein the inkjet ink has a lightness L* value of approximately 25 to approximately
 35. 3. The inkjet ink of claim 1, wherein the inkjet ink has a hue h° value of approximately 270 to approximately
 290. 4. The inkjet ink of claim 1, wherein the phthalocyanine dye is a sulfonated cyan dye.
 5. The inkjet ink of claim 4, wherein the sulfonated cyan dye is selected from the group consisting of a sulfoneamine, a sulfoneamide, and a sulfate group.
 6. The inkjet ink of claim 1, wherein the rhodamine magenta dye is Acid Red
 52. 7. The inkjet ink of claim 1, wherein the rhodamine magenta dye is selected from the group consisting essentially of Acid Red 52, Acid Red 289, Acid Red 388, and mixtures thereof.
 8. The inkjet ink of claim 1, wherein the mixture further includes a copper- or nickel-containing azo dye.
 9. The inkjet ink of claim 8, wherein the copper- or nickel-containing azo dye comprises Pacified or Non-Pacified Reactive Red
 23. 10. The inkjet ink of claim 8, wherein the copper- or nickel-containing azo dye comprises a nickel metallized naphthol azo triazole dye.
 11. The inkjet ink of claim 8, wherein the copper- or nickel-containing azo dye comprises a dye including the structure:

wherein M is H or a monovalent ion.
 12. The inkjet ink of claim 1, wherein the phthalocyanine dye is approximately 2 percent to approximately 4 percent by weight of the mixture.
 13. The inkjet ink of claim 1, wherein the rhodamine magenta dye is approximately 1 percent to approximately 2 percent by weight of the mixture.
 14. An inkjet ink, comprising: a mixture of phthalocyanine dye and rhodamine magenta dye in an ink vehicle, wherein the phthalocyanine dye is approximately 2 percent to approximately 4 percent by weight of the mixture, and the rhodamine magenta dye is approximately 1 percent to approximately 2 percent by weight of the mixture; wherein the phthalocyanine dye comprises a dye including the structure:

wherein each R group is independently H, SO₃H, SO₂NH₂, or SO₂NH-alkyl-OH, with the proviso that an average of from 2 to 6 R groups are other than H and at least one of the R groups is SO₂NH-alkyl-OH.
 15. The inkjet ink of claim 14, wherein the inkjet ink has a chroma C* value of approximately 60 to approximately
 90. 16. The inkjet ink of claim 14, wherein the inkjet ink has a lightness L* value of approximately 25 to approximately
 35. 17. The inkjet ink of claim 14, wherein the inkjet ink has a hue h° value of approximately 270 to approximately
 290. 18. The inkjet ink of claim 14, wherein the phthalocyanine dye is a sulfonated cyan dye.
 19. The inkjet ink of claim 14, wherein the rhodamine magenta dye is Acid Red
 52. 20. The inkjet ink of claim 14, wherein the rhodamine magenta dye is selected from the group consisting essentially of Acid Red 52, Acid Red 289, Acid Red 388, and mixtures thereof.
 21. The inkjet ink of claim 14, wherein the mixture further includes a copper- or nickel-containing azo dye.
 22. The inkjet ink of claim 21, wherein the copper- or nickel-containing azo dye is a nickel containing dye.
 23. A method of inkjet printing on a print media, the method comprising: providing a high chroma blue ink including a mixture of phthalocyanine dye and a rhodamine magenta dye in an ink vehicle, wherein the high chroma blue ink has a chroma C* value of approximately 60 to approximately 90; and ejecting drops of the high chroma blue ink on the print media with an inkjet printhead; wherein the phthalocyanine dye comprises a dye including the structure:

wherein each R group is independently H, SO₃H, SO₂NH₂, or SO₂NH-alkyl-OH, with the proviso that an average of from 2 to 6 R groups are other than H and at least one of the R groups is SO₂NH-alkyl-OH.
 24. The method of claim 23, wherein the high chroma blue ink has a lightness L* value of approximately 25 to approximately
 35. 25. The method of claim 23, wherein the high chroma blue ink has a hue h° value of approximately 270 to approximately
 290. 26. The method of claim 23, wherein the phthalocyanine dye is a sulfonated cyan dye.
 27. The method of claim 23, wherein the rhodamine magenta dye is Acid Red
 52. 28. The method of claim 23, wherein the rhodamine magenta dye is selected from the group consisting essentially of Acid Red 52, Acid Red 289, Acid Red 388, and mixtures thereof.
 29. The method of claim 23, wherein the mixture further includes a copper- or nickel-containing azo dye.
 30. The method of claim 29, wherein the copper- or nickel-containing azo dye is a nickel containing dye.
 31. The method of claim 23, wherein the phthalocyanine dye is approximately 2 percent to approximately 4 percent by weight of the mixture.
 32. The method of claim 23, wherein the rhodamine magenta dye is approximately 1 percent to approximately 2 percent by weight of the mixture. 